Throughout this application, various publications are referenced in parentheses by author and year. Full citations for these references may be found at the end of the specification immediately preceding the claims. The disclosures of these publications in their entireties are hereby incorporated by reference into this application to describe more fully the art to which this patent specification pertains.
Whitening and remineralization of teeth are directed to the enamel and dentin of teeth, as the art is currently understood. A current understanding of factors relevant to whitening and remineralization is discussed below.
Dental enamel and dentin are primarily composed of calcium phosphate in the form of calcium hydroxyapatite. Enamel is the hardest tissue in the human body due largely to its degree of calcification. The mineral hydroxyapatite makes up approximately 95% of the total weight of enamel, compared with 70% of the total weight of dentin and 45% of the total weight of bone. A small amount of epithelial-produced enamel matrix is present in enamel, about 1% of its total weight. Water is responsible for the remaining 4%. Enamel prisms or rods are highly calcified structural units. The enamel prisms are separated from each other by thin noncalcified sheaths of enamel matrix, the prism sheaths. As a rule, the enamel prisms run almost perpendicular from the dentin-enamel junction to the enamel surface, across the entire width of the enamel. This means that the length of the prism depends on its location. It is 3-4 mm at cusps or incisal edges, whereas at the cervix or neck of the tooth it may be negligible in length. The average width of an enamel prism is 4 microns, but the width varies. It is wider at the surface of the tooth and becomes narrower near the dentin-enamel junction. The hydroxyapatite crystallites in enamel are unusual in that they are 4 times larger in all dimensions than the hydroxyapatite crystallites in dentin, cementum, and bone. There is a gradual change in orientation of the crystal from parallel to perpendicular, head to tail, in cross-section. The average width of a prism sheath is 0.1-0.2 microns and consists of remnant glycoproteins of the enamel matrix (amelogenins and enameling)
Protease enzymes play a role in the development of enamel (Robinson et al., 1997). During development, the extracellular protein matrix comprises distinct proteins: amelogenins (the dominant group of the secretory stage enamel matrix), proline-rich non-amelogenins (amelins, ameloblastins or prism sheath proteins, comprising 10% of developmental proteins), enzymes (proteases, alkaline phosphatase, and carbonic anhydrase), and extraneous serum proteins of which albumin is the most notable. Albumin is degraded by proteases as enamel maturation continues. Any proteins or peptides remaining could potentially inhibit final crystal growth. If, during enamel formation, the organism is under some stress (e.g., disease or birth), the enamel deposited at the time may show some irregularities in its calcification and disruption of the enamel prisms, producing incremental lines (Retzius). The lines are darker in ground section due to its larger amount of enamel matrix and to a lesser degree to its calcification. Near the cervix of the tooth large numbers of regularly spaced incremental lines may be found in enamel, suggesting that something other than disease may be involved in the production of those lines (Moss-Salentijn, 1985).
Protease has been used in dental treatment as part of an enzymatic process for conditioning dentin surfaces to improve bonding between restorative materials and teeth (Balm and Stewart, U.S. Pat. No. 5,762,502).
Stains on teeth can be of the extrinsic or intrinsic type. The types of attractive forces involved in extrinsic dental stains include electrostatic and van der Waal forces, hydration forces, hydrophobic interactions, dipole-dipole moment forces, and hydrogen bonds. The strength of adhesion for chromogens and pre-chromogens are not well understood. A method of classification was attempted to further describe dental stains which involves three categories (Nathoo, 1997).
In category 1 stains, the color of the discoloration is the same as the color of the material (chromogen) that causes the stain. The substances of tea, coffee and wine contain tannins and are composed of polyphenols such as catechins and leucoanthocyanins. These materials generate color due to the presence of conjugated double bonds and are thought to interact with the tooth surface via an ion exchange mechanism. Also included in the mechanism of adherence of the chromogen to the tooth is the salivary pellicle, a protein structure adhering to enamel via calcium bridges.
In category 2 stains, pigmented materials bind to the pellicle or tooth and subsequently change color. An example of this would be the cervical yellow stain turning brown with age. A proposed mechanism for this change is through the further accumulation or chemical modification of pellicle proteins (denaturation by acids or detergents). Intensification may occur via a metal bridging mechanism. Category 2 stains are considered to be more difficult to remove than category 1 stains.
In category 3 stains, the binding of a colorless material to teeth can undergo chemical reactions or transformations. The colorless material is termed a pre-chromogen. Examples of this type of staining are the induction of chlorhexidene stain, browning of foods high in carbohydrates and sugars via a rearrangement of the carbohydrates and amino acids, termed the Maillard or non-enzymatic browning reaction, and staining from stannous fluoride.
Thus, extrinsic stains result from chromogens binding either to enamel or probably more so to pellicle. The removal of a pellicle layer via a bleaching system will present a whiter tooth. The pellicle is a natural occurring biolayer and will re-establish itself if removed. It will do so with minimal chromogen build-up.
Intrinsic stains include phenomena occurring both before and after eruption of the tooth from the alveolar bone into the oral cavity. Pre-eruptive phenomena include endemic fluorosis, tetracycline staining, dentinogenesis imperfecta, and amelogenesis imperfecta. Post-eruptive phenomena include pulpal hemorrhaging, and deposition of secondary dentin or metals in a tooth from an amalgam restoration.
Various approaches to bleaching teeth have been proposed or used (e.g., Fischer, U.S. Pat. Nos. 5,725,843, 5,746,598). However, tooth bleaching does have side effects. The most common side effect is sensitivity and discomfort following treatment with a peroxide formulation. The incidence and severity of symptoms are dependent on the concentration of the peroxide formulation and dentine permeability. Although there may be no evidence of pulpal damage in humans, obliteration of odontoblasts, hemorrhage, inflammation and internal resorption of dentin were reported in dog tooth pulps (Seale et al., 1981). The differences in observed changes in humans can be explained by the average thickness and morphology of enamel and dentin. Patients who have large or poor restorations, cervical erosion, enamel cracks or similar problems require special attention. Fluoride treatment of eroded cervical areas, sealing of restoration, and premedication with an analgesic may prove helpful in treating patients with these findings (Nathanson, 1997).
Bleached enamel has demonstrated slight morphologic surface alterations under scanning electron microscopy (Ernst et al., 1996). Enamel microhardness is significantly decreased with a common bleaching agent, 10% carbamide peroxide (Opalescence(copyright)). High concentration fluoride application was found to restore hardness to enamel specimens (Attin et al., 1997). The amount of calcium lost from enamel exposed to 10% carbamide peroxide has been quantified via an atomic absorption spectrophotometer. Teeth exposed to carbamide peroxide lost an average of 1.06 micrograms/mm2. This amount is small and may not be clinically significant (McCracken and Haywood, 1996).
Remineralization of teeth has been used when demineralization occurs naturally, for example in association with dental caries or dental hypersensitivity. In these procedures, remineralization has been achieved using either one-phase or two-phase compositions comprising calcium and phosphate, to which fluoride can be added (e.g., Usen and Winston, U.S. Pat. No. 5,605,675; Winston and Usen, U.S. Pat. Nos. 5,603,922, 5,614,175). Fluoride is known to enhance remineralization.
Because demineralization also occurs during tooth bleaching, efforts have been made to consider remineralization mechanisms. Saliva, or artificial saliva, can remineralize teeth after bleaching (Attin et al., 1997; Lys-Masanes and Goldberg, 1989; Zhu, 1991), and the effect can be enhanced by the addition of gluconate solution (Lebedeeva and Galchenk, 1981) or fluoride (Attin et al., 1997; Lys-Masanes and Goldberg, 1990). It has also been reported that bleached teeth can be recalcified using calcium phosphate solution (Zhu, 1991).
Commercial products for whitening teeth have been developed. These include Enamelon(copyright) xe2x80x9cCalcium Whitening Systemxe2x80x9d toothpaste, the ingredients of which include phosphoric acid, anhydrous dicalcium phosphate, sodium fluoride, and sodium gluconate (Enamelon, Inc., Cranbury, N.J.), and Rembrandt(copyright) xe2x80x9cLow Abrasion Whitening Toothpaste,xe2x80x9d the ingredients of which include papain, dicalcium phosphate, and sodium monoflurophosphate (Den-Mat Corp., Santa Maria, Calif.).
The present application discloses advantageous compositions for whitening and remineralizing teeth, wherein the three key components are a whitening agent, a protease enzyme, and a remineralizing agent.
Advantageous compositions for whitening and remineralizing teeth are disclosed, which comprise a whitening agent, a protease enzyme, and a remineralizing agent.
Advantageous kits and methods are disclosed for applying the whitening and remineralizing compositions described herein to teeth.
The compositions can be applied using different carriers which include, but are not limited to, a chewing gum, a toothpaste, a lozenge, a powder, a gel, a viscous gel, an ointment, a cream, a liquid, a mouthwash, and a candy.
The compositions, kits, and methods described herein can also be used to treat dental sensitivity and dental caries.
In alternative forms, the compositions, kits and methods described herein can be used in a dental office, at home, or in a veterinary setting.